Since the beginning of the 1980s there has been an increasing demand for frozen confectionery products and desserts such as ice cream and related products which have a reduced calorific value.
Reducing the amount of fat in the ice cream would be the most effective way of reducing the calorific value as it has a calorific value per gram which is higher than that of carbohydrates. However, by reducing the amount of fat in the ice cream, considerable difficulties arise as its effectiveness in stabilising the structure is reduced. Insufficiently stable products are not robust to the cold chain and are unacceptable to consumers.
There are three phases that contribute to structure and therefore stability of ice cream, namely fat, ice and the matrix, which includes stabilisers.
In low fat ice cream where the structuring contribution of fat has been decreased, to maintain or improve product stability the contribution of either or both the ice and matrix phases must be increased. However, while increasing the ice content or stabiliser level may improve product stability this has undesirable effects on the texture of the ice cream. For example if the ice content is too high the ice cream will be hard and icy, whereas if the stabiliser level is too high the ice cream will have a gummy, gel-like texture as well as off flavours associated with the stabilisers.
In our co-pending application PCT/EP2005/010579, we have used ice structuring proteins (ISPs) to significantly improve the stability of low fat frozen confectionery products without the deleterious effects on texture and/or taste seen with previous approaches. However, our further investigations have shown that in low fat systems with standard levels of stabilisers and emulsifiers that the addition of ISP has an adverse effect on the structure of the gas phase, giving rise to irregular shaped gas cells and ice crystals are observed growing into the gas cells. This has an adverse effect on product texture, such as smoothness.